Contents lists available at ScienceDirect Toxicology in Vitro journal homepage: www.elsevier.com/locate/toxinvit Metabolomics and cytotoxicity of monomethylhydrazine (MMH) and (E)-1, 1,4,4-tetramethyl-2-tetrazene (TMTZ), two liquid propellants Laetitia Guyot a , Christelle Machon a , Myléne Honorat a , Brigitte Manship b , Charlotte Bouard b , Arnaud Vigneron b , Alain Puisieux b , Emilie Labarthe c , Guy Jacob d,e , Anne Dhenain d , Jérôme Guitton a,f , Léa Payen a,b,f, ⁎ a Hospices Civils de Lyon, Centre Hospitalier Lyon-Sud, Laboratoire de biochimie-toxicologie, F-69495 Pierre Bénite, France b UMR INSERM U1052/CNRS 5286, Centre de Recherche en Cancérologie de Lyon, Centre Léon Bérard, 69373 Lyon, France c CNES Launcher Directorate, 52 rue Jacques Hillairet, 75612 Paris, France d Université Lyon 1, Faculté des sciences et technologies, UMR CNRS 5278, Hydrazines et Composés Energetiques Polyazotés, 69622 Lyon, France e Airbus Safran Launchers, Centre de Recherches du Bouchet, 9 Rur Lavoisier, 91710 Vert le Petit, France f Université Lyon 1, ISPBL, Faculté de pharmacie, Laboratoire de Toxicologie, 69373 Lyon, France ARTICLE INFO Keywords: (E)-1,1,4,4-tetramethyl-2-tetrazene (TMTZ) Monomethylhydrazine (MMH) Alkyltetrazene Liquid propellant ABSTRACT Hydrazine-based liquid propellants are routinely used for space rocket propulsion, in particular mono- methylhydrazine (MMH), although such compounds are highly hazardous. For several years, great efforts were devoted to developing a less hazardous molecule. To explore the toxicological effects of an alternative com- pound, namely (E)-1,1,4,4-tetramethyl-2-tetrazene (TMTZ), we exposed various cellular animal and human models to this compound and to the reference compound MMH. We observed no cytotoxic effects following exposure to TMTZ in animal, as well as human models. However, although the three animal models were un- affected by MMH, exposure of the human hepatic HepaRG cell model revealed that apoptotic cytotoxic effects were only detectable in proliferative human hepatic HepaRG cells and not in differentiated cells, although major biochemical modifications were uncovered in the latter. The present findings indicate that the metabolic me- chanisms of MMH toxicity is close to those described for hydrazine with numerous biochemical alterations induced by mitochondrial disruption, production of radical species, and aminotransferase inhibition. The al- ternative TMTZ molecule had little impact on cellular viability and proliferation of rodent and human dermic and hepatic cell models. TMTZ did not produce any metabolomic effects and appears to be a promising putative industrial alternative to MMH. 1. Introduction Propellants using hydrazine and its derivatives are widely used in the aerospace and defense industries. Indeed, these compounds are perfectly adapted for applications that need to be both reliable and accurate, such as approach maneuvers in space. For instance, hydrazine is used as a monopropellant for launcher trajectory correction and for the propulsion of small satellites, while monomethylhydrazine (MMH), a bipropellant used in combination with nitrogen tetroxide, is found in storable propellant engines for launchers and in apogee kick motors of artificial satellites. The latter is also used in the Automated Transfer Vehicle, the European cargo that supplies the International Space Station, the orbit of which is raised by 30 km per year using MMH. Currently, MMH and the unsymmetrical 1,1-dimethylhydrazine (UDMH) are the principal molecules used on a large industrial scale for spatial applications (Fig. 1). The lethal doses (LD50) of MMH and UDMH are 33 mg/kg (IP) (National Academies, 1974) and 250 mg/kg (IP), respectively, reflecting an important metabolic toxicity (Witkin, 1956). Indeed, animals exposed to these compounds display important liver and cardiotoxicity, and although no carcinogenic properties have clearly been demonstrated, MMH and UDMH also display genotoxic properties (Clark et al., 1968), including the formation of DNA methyl adducts, a positive Ames test in several strains of bacteria, and an in- crease in micronuclei upon exposure (Carlsen et al., 2009; Choudhary and Hansen, 1998; Reddy et al., 2010). In addition, exposure to 0.05–0.5 ppm UDMH for very short or longer periods of time is known to increase the incidence of cancer in mice and rats (Carlsen et al., 2007). In contrast, hydrazine is highly tumorigenic and carcinogenic. It has a great reactivity with a wide variety of reagents including halo- gens, alkali metals and sulfur dioxide (Biancifiori et al., 1964; https://doi.org/10.1016/j.tiv.2018.06.005 Received 6 February 2018; Received in revised form 16 May 2018; Accepted 4 June 2018 ⁎ Corresponding author at: Université Lyon 1, ISPBL, Faculté de pharmacie, Laboratoire de Toxicologie, 8 avenue Rockefeller, 69373 Lyon, France. E-mail address: lea.payen-gay@univ-lyon1.fr (L. Payen). Toxicology in Vitro 52 (2018) 70–86 Available online 07 June 2018 0887-2333/ © 2018 Published by Elsevier Ltd. T